The present invention relates to automated methods for cutting and stripping insulation or other external layers from an electrical conductor. More specifically, the invention relates to novel insulation cutting and stripping methods wherein one or more blades are moved in a predetermined manner with respect to an insulated conductor held in a fixed position to cut the insulation to a certain depth, less than that of the conductor, and thereafter severing and removing the slug of insulation.
One type of apparatus for cutting one or more layers of material at a predetermined position on a circular cross section conductor is that employing a pair of blades having parallel cutting edges which are rotated about the axis of the conductor as they are moved toward one another. Examples of such apparatus are found in the aforementioned parent application and U.S. Pat. No. 4,745,828 discussed therein. The wire is gripped and held by guide means in a fixed reference position as the rotating blades are moved together until they are spaced by a distance very close to the diameter of the conductor, or other layer of material within the layer being cut. The depth of cut is controlled by a selectively programmable microprocessor.
It is essential that both the longitudinal and lateral positions of the conductor be accurately fixed and maintained during the cutting operation, and that the depth of cut be controlled and repeatable to within very close tolerances, e.g., 0.001", since even minute nicks in the conductor or other inner layers, e.g., woven metal braid, are unacceptable. This is further complicated by the fact that conductors are sometimes not symmetrically located within the one or more layers to be cut and stripped, in which case the conductor is frequently nicked or scored by the blades and must be rejected.
A principal object of the present invention is to provide a method and apparatus for cutting and stripping insulation or other protective layers from electrical conductors without danger of nicking, scraping or scoring the conductor by the movable blades.
Another object is to provide a method and apparatus for cutting and .stripping insulation from electrical conductors which does not require extremely precise lateral positioning of the conductor in order to avoid the possibility of damaging the conductor during the cutting and stripping operation.
Other objects will in part be obvious and will in part appear hereinafter.